On High Jump, do not press R1 going up the ramp. When you leave the ramp, and if you have enough air, you will go soaring through the bars and crash into the ground. Note: Your car will get totaled.
Disable active cheats
Enter RAGDOLL as a name. After entering it, you may rename your profile to any desired name.
Easy money
Run over obstacles to get extra money (for example, beams on construction sites and wooden fences).
Try not to finish in last place. You still get bonus money if you are in fourth through seventh place.
When you first start career mode, buy the Grinder (the third or fourth car that looks like a Mustang). Do about half the races in the Bronze class. Upgrade your car with the money you have, then go to the Bonus class races and select the High Jump. When you start, go down the ramp and over the first hill/jump as fast as you can; but do not hit the nitro/launch yet. As soon as you land off the first hill, hold Nitro to charge up as you go up the second and final ramp. At the top, let go. If done correctly, your driver should fly very high and over the top of the whole ladder thing in front of you, and perhaps even over the net that is supposed to catch you. This is the best combination of car and technique to score huge in this challenge. For some reason you cannot do this with the faster cars that are unlocked later. Keep your Grinder a little bit longer after completing the Bronze class and earn as much money as you can by doing the High Jump stunt challenge.
Buy any car desired when starting career mode and complete the Bronze class events. However, do not spend too much on your car and try to save at least $4,000 to 5,000 dollars by doing so. You will earn about $4,000 upon completion of the Bronze class if you do well. Completing the Bronze class will also unlock new cars. Go to the car dealer and buy the Road King or a better car if desired. Once you do, go to the Bonus Events and enter the Oval Ring thing (the second one down on the far right column). This is just a simple race against other drivers where you drive as fast as you can around a big dirt oval. When the race starts, break away from the pack and just hold down the gas. Drive around the ring as smoothly as you can, avoiding the occasional stack of tires and junk on the side of the track. You do not need to smash through it because earning a nitro boost here is pretty much useless, and will only get you into a wreck by using it. Just stay in first as the other drivers muck about behind you plowing through rubble and smashing into each other. When you cross the finish line first after eight laps you will receive an easy $1,500. Keep doing this to earn money to upgrade your car faster and get an edge over the competition in the real races.
Fly off map
Enable the "All cars and tracks" code, then do a quick race. Choose one of the last six cars (they are the fastest) and choose the "Crashalley Run" race in the Bonus Class races. It is the last one on the right. When the race starts, do about the first two laps so that you have a nitro boost. You should have earned one by now, as there are many cars flying around to smash into. Once you have some nitro, go as fast as you can down one of the bumpy straightaways. When the turn comes up, hit the nitro and blast into the wooden and concrete barriers that make up the edge of the track slightly to the right. Your driver should fly out and go far away from the track, going over the edge of the map and fall into blackness. The game will reset after a while.
Fly through walls
During the Bonus "High Jump" race, notice when your driver flies through the air and is about to go into the seating area of the stadium, he will hit an invisible wall and falls to the ground, or get caught in the big net. To fly through the seating area and other parts of the stadium, use the following trick. Use the car called the "Trasher" and enter the Highjump stunt. For some reason the Trasher gets you the most air when going off the ramp. Go off the jump ramp and launch as usual, except just before the car leaves the ramp steer slightly to the right. Release Nitro to launch your driver. If you are lucky, he will somehow bypass the invisible wall, fly through the seats, and hit the ground under it. How high you went will be recorded as usual. Also, if you go high enough (over the 100m mark on the ladder) you can see the edge of the map and beyond.
Nitro boost
To earn an easy nitro boost, do not try to plow through lots of big heavy objects on the side of the road. This only slows you down and you might get stuck in it. Instead, look for cones lining the track and hit those small cardboard boxes. Also signs are good to run through. These objects do not slow you down, and will earn nitro. Also, if you are going to slam into junk on a turn, try and slide sideways into it. You more or less will slide or bounce of it, losing less speed and you will not get stuck. This also works well with roadside fences, where you can just rub up on them and knock them down sideways instead of ramming through them directly.
At the first race from the left list, hit the scaffolds under the bridge to get all the nitrous you can. Be careful; there is a ladder at the right scaffold. If you hit it, you will slow down a lot.
Re-enable codes
After you enable a code, it will normally be disabled. However if you reset the PlayStation 2, remove the memory card, enable the code again, then put the memory card back in and load your profile, it will work again.
Stuck in fence
If you go far enough in the High Jump bonus game (hold R1 at the bottom of the ramp, then release about half a second off the ramp) you will hit the fence wall and get stuck in it. If you wait long enough, the rag doll person will start sliding down the fence.
Unlock Everything
Create a new profile and use the following to enable the cheats:
GIVEALL: Unlocks everything
GIVECASH: Lots of dash
The words will disappear when you select DONE then type in your proper player name and save the profile with the cheats active. There is also RAGDOLL which seems to disable the cheat input.
Unlocking parts
You can unlock all the parts you want and upgrade your car to the max without having to cheat by just saving or earning a lot of money. Do previously completed races and bonus events to earn some cash then buy a performance part. You will notice the next part of the same type (the better version of the one you just purchased) now becomes unlocked. If you keep buying every part you can find, more parts will keep becoming available for you to buy.
Breaking the bars...